Understanding How to Effectively Use Compression
|By CUS and AMIR SAID (SA'ID)|
Mixing hip hop/rap music offers its own set of challenges. From rupturing kick drums to rumbling bass lines, hip hop/rap music doesn't always fit neatly into traditional approaches to mixing. Sure, the same sonic tools/effects are in play when mixing hip hop/rap music, just like any other music form. But how these sonic tools are applied and used in hip hop/rap music (or any other music form) can mean the difference between something sounding pleasing to the ear or something outright crummy. And there is no other effect that can make or break this difference than compression.
In hip hop/rap music, where the dynamic range is often a blend of sampled sounds, compression is the most commonly misused sonic tool. So to truly understand how and when to use compression more effectively—that is, not abuse and misuse it—, it is important to first get a working knowledge of what compression actually is and does. Fundamentally, compression is about controlling the dynamic range of an individual track or song in a way that keeps everything contained in the same zone, so to speak. Indeed, a good way to look at compression is to view it as a process of effective containment. What compression does, in a basic control approach, is it pretty much takes any sound and contains it from spilling out of a desired range of sound and color. In this way, compression keeps the most common hip hop/rap music production sounds—high velocity kicks, snares, bass lines, samples—from varying too wide in range; it makes everything stick together like glue.
Further, one of the most basic ideas of compression is to boost up the quieter dynamics in a mix and to simultaneously “squash” (reduce/neutralize) the peaks. The aim of this is to be able to turn up the overall track volume, getting the much sought after bang and punch. For instance, effective compression can increase the presence of a thin bass line, making it sound fat and warm. But the misuse of compression can make that very same bass line sound distorted and out of place—unstuck.
Having understood what compression is it’s good to break down how it works. A typical compressor (hardware or software) has basic parameters through which compression is applied to a sound (signal); they are: Threshold, Input, Ratio, Attack, Release, Input, and Output. Threshold sets the level at which a compressor goes into action; it’s the point at which the compressor starts to work. Think of it as a virtual line of decibels (dB), that once crossed, the compressor goes to work. Likewise, whenever a signal falls below the set threshold, compression stops. Because threshold works in tandem with a compressor's input level, which controls the strength of a signal coming into the compressor, the stronger the signal, the sooner the threshold level is reached.
Ratio represents the level (amount) of compression that will be applied to any signal that exceeds the threshold setting. Any sound signal coming in above the set threshold will be affected in accordance to the ratio setting.
Attack, measured in milliseconds (ms), represents the time that it takes before the compression actually happens, once a sound signal reaches the threshold. The shorter the time, or rather the faster the attack, the quicker and/or more harsh the compression. A quick attack is useful in neutralizing kick peaks, which in turn allows the overall level to be raised. Generally speaking, you want compression to happen as soon as possible. But remember, there are no hard rules on this; the sound and vibe of a track that you’re going for will dictate how you adjust compression settings.
Release, measured in ms, determines how long it takes for a compressor to let go of a signal, once it has dropped below the set threshold. With a longer release time, the compression holds on longer to the signal that it’s applied to. A long release time is especially useful for adding sustain and extended nuance to a signal. A too fast release setting can result in “pumping” (where the compression can be heard). Here, it’s also worth noting that’s it’s a good idea to always have the compressor’s meter set to “GR” (Gain Reduction). This way you’re seeing exactly how much the sound being compressed is cutting back. It is also a good view of how fast/slow the compressor is attacking and/or releasing.
Output represents the overall output level of an applied effect.
Through the brief breakdown of the basic parameters of a typical compressor, it’s easy to see the upside of compression. But there can also be a downside to compression. One common mistake is having the threshold a little bit too harsh and pushing towards the negatives too much, resulting in a sound that is smothered or struggling to get light. Perhaps the best way to tell if something has been compressed too much is by checking the velocity of the sound. That is, if the sound is coming off dull or it’s noticeably losing significant volume, then it has been compressed too much. Though volume does increase some during compression, it should not be the source for controlling volume.
Because of the unique sonic nature of hip hop/rap music, there are really no magic compression settings for any one sound or group of sounds. Moreover, compression can be used in different ways; you’re only limited by your imagination. Therefore, like many processes of beatmaking and recording/mixing, experimentation and trial and error is a must. In order to find compression settings that work well with your taste and style of production/mixing, you have to try compressing different sounds with different settings, being mindful to avoid those things that flatten and dull your overall sound. And with a good grasp of what compression is and how it works, you’re well on your way to finding your own unique default settings. In the end, that's really the best way to make compression your friend and not your foe.
Some useful compression guidelines:
Begin with short attack and release times, then adjust as needed.
Begin with a 4:1 ratio, then adjust as needed.
Because bass, especially in hip hop/rap music begs to be consistent, think heavier compression on bass sounds.
Compression isn’t just a tool for controlling sound; it can be used to add color as well.
As with any sonic tool, use compression in the ways that help you get that sound and feel that you want.
Avoid using compression simply as a tool to make sounds louder.
*Feel free to leave comments and add your own compression guidelines.